This invention relates to high velocity liquid discharge devices in general and, in particular, to a new and useful liquid jet discharging method and to a pulsating liquid jet gun, comprising a free piston which is movable in a cylinder bore between a combustion space and a liquid chamber and which is driven during the working stroke by the hot reaction gases of a propellant charge which is periodically ignited in the combusion space, and actuates a definite amount of liquid, thereby, producing a high speed liquid jet, with the liquid being refilled into the liquid chamber prior to every ignition of the propellant.
With pulsating water guns of the prior art, in order to increase the pressure, the free piston is usually designed as a differential pressure piston. The propellant gas reaction is initiated, in accordance with the Otto principle, by an electrical spark plug or a pyrotechnic primer composition and propagates outwardly starting from the point of initiation. In order to attain the safe high pressure refilling of the liquid chamber, this design requires a highly expensive construction and control for the operation of the free piston.
Such devices have the further drawback that the retarded building-up of pressure in the combustion space adversely affects the maximum obtainable pressures or pressure increase rates and, thereby, also the shot effect of the liquid jet, and this is true, even if high energy monergolic or non-hypergolic propellant systems in the form of one or more separate liquid propellant components, for example, are used.